Laboratory Testing for the Antiphospholipid Syndrome

Abstract

Antiphospholipid syndrome (APS) is an autoimmune disorder characterized by thrombosis or recurrent pregnancy losses. It is a significant cause of pregnancy morbidity manifesting as recurrent miscarriages in young females of reproductive age-group. Classification criteria for definite APS are met when at least one clinical criterion, either thrombosis (arterial, venous or small vessel) or pregnancy morbidity, and one laboratory criterion (persistent positivity for Lupus anticoagulant, anticardiolipin or anti-beta 2 Glycoprotein 1 antibodies on two or more occasions at least 12 weeks apart) are present. For detection of Lupus anticoagulant, at least 2 assays- diluted Russell viper venom time and activated partial thromboplastin time based test using silica as an activator are recommended. Anticardiolipin and anti-beta 2 Glycoprotein 1 IgG/IgM antibodies are detected by enzyme linked immunosorbent assay, chemiluminescence or fluorescence enzyme immunoassay. Testing for lupus anticoagulant may be challenging while in acute phase of thrombosis and on anticoagulant therapy. Laboratory participation in external quality assurance exercises is highly recommended for standardization and inter-laboratory agreement of laboratory assays. In this chapter we discuss the key issues in APS pertaining to women with a focus on laboratory testing.